Mendelian Genetics Pedigrees & Karyotypes

TEKS 6 D & F

TAKS Objective 2 – The student will demonstrate an understanding of living systems and the environment.

TEKS Science Concepts 6 D & F

The student knows the structures and functions of nucleic acids in the mechanisms of genetics. The student is expected to

(D) compare genetic variations observed in plants and animals

(A) identify and analyze karyotypes.

$For Teacher’s Eyes Only

Mendelian Genetics

Pedigrees

Karyotypes

Student Prior Knowledge

Students should be familiar with the components associated with body systems TEKS 6.10 (C)identify how structure complements function at different levels of organization including organs, organ systems, organisms, and populations and the functions of these systems.

5 E’s

MENGAGE

Comical X and Y Chromosome Maps

Comic relief and fun discussing differences on the X and Y chromosome maps.

NEXPLORE

Explore 1

Fundamentally Genetics

In groups of two, students will look at each other to determine whether they are dominant or recessive for specific, identifiable traits.

Explore 2

Bugs, Bugs, Bugs

Genes for traits are encoded and arranged linearly on structures called chromosomes found in the nuclei of most cells. When organisms reproduce, the resulting offspring should receive an equal number of chromosomes from the mother and the father.

In this activity students will use the chromosomes and Bug Traits Key to determine the genotype and phenotype of the offspring.

Explore 3

Begin Wisconsin Fast Plants Genetics Lab

Explore 4

Predicting Outcomes of One Trait Crosses

Monohybrid Punnett Squares

Upon completion of this activity, students will be able to predict the outcomes of various monohybrid crosses.

Predicting Outcomes of Two Trait Crosses

Dihybrid Punnett Squares

What predictions can be made when looking at two traits. Students will complete this activity to predict the outcomes of various dihybrid crosses.

EXPLAIN

Complete the Mendelian Genetics PowerPoint presentation with your student with discussion and the completion of the following questions.

LELABORATE

Elaboration 1

Exceptions to Mendel’s Rules

Students will complete various Punnet squares problems that will involve the following types of inheritance: Sex-Linked, Multiple Alleles, Co-Dominance, Incomplete Dominance

Elaboration 2

Who’s the Parents?

Obtain WARD’S Scientific lab kit Simulated ABO Blood Typing Lab Activity from www.wardsci.com Item #36 V 0022

Upon completion of this lab, students will:

determine the ABO blood types of two sets of parents and two newborn children

examine the genetic relationships possible between the parents and children

match the “mixed up” children with their proper parents.

áEVALUATE REWRITE

TAKS Objective 2 page 5

Fundamentally Genetics

Bugs, Bugs, Bugs

Predicting Outcomes of One Trait Crosses

Monohybrid Punnett Squares

The Punnett Square:

The Punnett square is a chart, used by geneticists, to help determine the chances of an offspring receiving a particular characteristic. The Punnett square will not tell you how many offspring will develop, or the order in which they will be born. B = brown hair and b = blonde hair.

Example: ------Bb X Bb ------Parents who are heterozygous for Brown hair.

Gametes: ------B and b ; B and b------Each parent produces 2 gametes.

Punnett Square:

Gametes ------|----> / B / b
B / ------ / ------
B / ------ / ------

1. What are the chances of the offspring being homozygous brown haired? ______.

2. What are the chances of the offspring having blonde hair? ______.

3. What are the chances of the offspring being heterozygous brown haired? ______.

4. What is the genotypic ratio? ______.

5. What is the phenotypic ratio? ______.

6. What is the dominant gene? ______.

7. Is there a heterozygous blonde haired offspring? ______. Why? ______

Questions:

8. If curly hair is dominant to straight hair, what letters will we use to show these genes?

9. If a heterozygous curly haired male marries a straight haired female, what would there genotypes look like using the letters in question 8 ? ______X ______.

10. What would be the gametes for the male parent? ______

11. What would be the gametes for the female parent? ______

12. Work out the Punnett square in the space below and answer the following questions.

Gametes ------|----> / B / b
B / ------ / ------
B / ------ / ------

13. What are the chances of the offspring being homozygous curly haired? ______.

14. What are the chances of the offspring having straight hair? ______.

15. What are the chances of the offspring being heterozygous curly haired? ______.

16. What is the genotypic ratio? ______.

17. What is the phenotypic ratio? ______.

18. What is the dominant gene? ______.

19. Is there a heterozygous straight haired offspring? ______. Why?______

20. If yellow pods are dominant to green pods, what letters will we use to show these genes?

21. If a heterozygous yellow male is crossed with another heterozygous yellow female, what would there genotypes look like using the letters in question 20 ? ______X ______.

22. What would be the gametes for the male parent? ______

23. What would be the gametes for the female parent? ______

24. Work out the Punnett square in the space below and answer the following questions.

Gametes ------|----> / B / b
B / ------ / ------
B / ------ / ------

25. What are the chances of the offspring being homozygous green? ______.

26. What are the chances of the offspring being yellow? ______.

27. What are the chances of the offspring being heterozygous yellow? ______.

28. What is the genotypic ratio? ______.

29. What is the phenotypic ratio? ______.

30. What is the dominant gene? ______.

31. Is there a heterozygous green offspring? ______. Why? ______

Predicting Outcomes of Two Trait Crosses

Dihybrid Cross

Independent Assortment: Mendel's 4th Law explains that , when gametes are formed, genes move into these gametes independently of other genes. This occurs only if these genes are on different chromosomes.

Dihybrid Cross: A genetic problem with two different characteristics.

T = Tall, t= short.------B = brown hair, b = blonde hair

Parents: / TTBB-- / X / ttbb
Gametes: / TB / -tb

Punnett Square:

Gametes / tb
TB / TtBb

Notice that each parent produces gametes with 2 genes, one from each pair. Never do we have more than one gene from each pair in a gamete. We are now going to mate two of the offspring produced in the above problem.

Parents: --- / -TtBb / ---X -- / TtBb
Gametes:- / TB--- / TB
Tb - / -Tb
tB / tB
tb / tb

Punnett Square:

Gametes / TB / Tb / tB / tb
TB / TTBB / TTBb / TtBB / TtBb
Tb / TTBb / TTbb / TtBb / Ttbb
tB / TtBB / TtBb / ------/ ------
tb / ------/ ------/ ------/ ttbb

a). What is the phenotypic ratio: ______

b). What is the genotypic ratio? ______.

Problem:

Cross a homozygous tall, heterozygous brown haired male with a heterozygous tall, blonde haired female.

------______X ______

Gametes: ------______------______

Punnett square:

Gametes / TB / Tb / tB / tb
TB / TTBB / TTBb / TtBB / TtBb
Tb / ------/ ------/ ------/ ------
tB / ------/ ------/ ------/ ------
tb / ------/ ------/ ------/ ttbb

a). What is the phenotypic ratio ? ______

b). What is the genotypic ratio ? ______

c). How many offspring are homozygous for both characteristics ? ______.

d). How many offspring are heterozygous for both characteristics ? ______.

Mendelian Genetics Guided Notes

Mendel and Genetics

Directions: Answer the following questions completely.

1. The ______is a chart, used by geneticists, to help determine the chances of an offspring receiving a particular characteristic.

2. Before parents can mate successfully, each one must produce special cells called ______.

3. These special cells contain ______the normal number of chromosomes of regular body cells.

4. ______is considered the father of Genetics.

5. DNA contains the code for every ______that an organism can produce.

6. According to Mendel, ______pairs separate during gamete formation.

7. Mendel called traits that appeared more often than its alternate ______.

8. This trait or characteristic is assigned a(n) ______letter to distinguish it from its recessive allele.

9. If two alleles for a characteristic are identical, the organism is said to be ______for that trait.

10. Another word for hybrid is ______.

11. The ______is the outward appearance of an organism’s trait.

12. Tt or BB represents the ______of an organism.

13. An alternate form of a gene is called its ______.

Read the following problem, solve it by working out the Punnett square, and then answer the questions that follow.

Mate a rooster that is homozygous for curly feathers with a hen that is heterozygous for straight feathers. Straight feathers are dominant to curly feathers.

1. Choose a letter to represent the allele curly feathers ______and one for the allele straight feathers ______.

2. Write out the genotypes of each parent below:

______X ______

3. List the gametes for each parent: ______and ______

Show all work for full credit.

Gametes ------|----> / B / b
B / ------ / ------
B / ------ / ------

4. What are the chances of the offspring having curly feathers? ______.

5. What are the chances of the offspring having straight feathers? ______.

6. What is the genotypic ratio? ______.

7. What is the phenotypic ratio? ______.

8. Being able to roll your tongue into a u shape is caused by a dominant gene. The recessive allele does not allow this to happen. Two parents, one with the ability to roll her tongue and the other one cannot roll his, mate and have two children. All of the children cannot roll their tongues. What is the genotype of each parent? ______and ______.

Mendel tried to determine if green seed color was dominant to yellow seed color. The result of the experiment is found below. Examine the data, bar graph it, and answer the questions that follow.

Generation of Plants / Number of Yellow Seeds Produced per generation / Number of Green Seeds Produced per generation
P / 0 / 0
F1 / 0 / 100
F2 / 102 / 312
F3 / 303 / 879
F4 / 970 / 2900
F5 / 2,970 / 9,080

Graph Title: ______

1. What color appears to be the dominant allele? ______.

2. Why? ______

______

3. What is the phenotypic ratio of the above experiment? ______.

4. What is the dependent variable? ______.

5. What is the independent variable? ______.

6. Explain why the F1 generation contained all green seeds. ______

7. What was the genotype of the F1 generation? ______.

______

Exceptions to Mendel’s Rules

Multiple Alleles, Co-Dominance, Incomplete Dominance

Incomplete Dominance

Sometimes the masking effect of a dominant allele (gene) is not complete. This is evident in the case of the red and white 4 o'clock flower. If we mate a homozygous red flower (RR) with a homozygous white flower (WW), we would expect all the offspring to be red. Instead all of the flowers came out pink. Red did not completely mask the white allele. The red gene allows the production of red pigment, if it is in a homozygous condition. The white gene does not allow pigment production. If one R gene is present, half of the pigment is produced and a pink color appears. The genotype for pink colored flowers is RW. This condition also occurs in cattle, where the individual with the genotype RW is called a roan.

Define incomplete dominance ______

Give two characteristics that are governed by incomplete dominance?

______

Example ------RR ------X------WW

Punnett Square:

Gametes / W / W
R / RW / RW
R / RW / RW

1. What are the chances of having pink offspring ? ______.

2. What are the chances of having red offspring ? ______.

3. What are the chances of having white offspring ? ______.

4. What is the genotypic ratio ? ______.

5. What is the phenotypic ratio ? ______.

6. A farmer wants to mate two roans together. What are the genotypes of the these animals ? ______X ______

7. What would be the gametes for the male parent ? ______

8. What would be the gametes for the female parent ? ______

9. Work out the Punnett square in the space below and answer the following questions.

Gametes ------|----> / B / b
B / ------ / ------
B / ------ / ------

10. What are the chances of having red offspring ? ______.

11. What are the chances of having white offspring ? ______.

12. What are the chances of having roans ? ______.

13. What is the genotypic ratio ? ______.

14. What is the phenotypic ratio ? ______

15. What information would let a person know that a characteristic is governed by incomplete dominance? ______

______

Multiple Alleles and Co-Dominance

16. Define multiple alleles. ______

______.

17. What are the genotypes for Blood type A? ______, Type B? ______, and Type O? ______.

18. What is the genotype of the universal donor? ______

19. A man with heterozygous B type blood marries a women with heterozygous A blood. What are the chances of them having children with type A blood? ______, Type B blood? ______, O type blood? ______. Work out the problem below.

Punnett Square:

Gametes ------|----> / B / B
B / ------ / ------
b / ------ / ------

20. Of the three alleles for blood type which two are codominant? ______.

21. At a local hospital, Mr. and Mrs. Lump had a child at the same time as Mr. and Mrs. Bump. The Lumps had a boy and called him Bill, while the Bumps also had a boy and called him Tony. A few weeks past and the Bumps claimed the babies were switched. They sued the hospital and all 6 individuals were asked to get their blood tested. The results of the tests were: Mr. Lump had A type blood, his wife had B type blood, and Bill had A type blood. Mr. Bump tested for O type blood, his wife had AB blood, and Tony had O type blood. Was there a switch? ______. How do you or do you not know?______

Work the punnett square for each of the parents below:

The Bumps: ______X ______. The Lumps: ______X______